This schema defines the element qualified by
the 'http://jabber.org/protocol/xhtml-im' namespace.
The only allowable child is a element qualified
by the 'http://www.w3.org/1999/xhtml' namespace. Refer
to the XHTML-IM schema driver for the definition of the
XHTML 1.0 Integration Set.
Full documentation of this Integration Set is contained in
"XEP-0071: XHTML-IM", a specification published by the
XMPP Standards Foundation.
http://www.xmpp.org/extensions/xep-0071.html